Many articles, particularly those that are worn about the waist, include a side member that permits the article to be secured about the waist of the wearer. In baby diapers, for example, it is common to provide an elastic member containing a hook-and-loop type fastener which permits the diaper to be secured to the infant or child and, if necessary, released and re-positioned or re-fastened. These elastic members are typically attached at one end to the diaper chassis and contain the hook-and-loop or adhesive tape element on the free end. A mating member for the fastener (be it hook-and-loop or adhesive) is positioned on the front portion of the diaper. In use, the diaper is positioned behind the baby and the side tabs are drawn forward and secured to the front portion of the diaper.
In the diaper field, the elasticized side members are generally classified as side tabs, side ears, or side panels. A side member is typically considered a “tab” if its width is around 60 mm or less and an “ear” if its width is greater than about 60 mm. A side “panel” is generally an integral member forming the side of the diaper and, unlike “tabs” or “ears” is not re-fastenable or re-positionable. Side panels are typically found on “pull-up” style training pants and can be formed by seaming or otherwise joining together ears located on the front and back portions of the diaper chassis.
Apart from their dimensions, side “tabs” and side “ears” also differ functionally. A side tab is generally employed on a diaper chassis having an hourglass shape—wider at the front and back and narrower in the middle (crotch) area. The enlarged chassis portions of the hourglass shape form not only the front and back of the diaper, but also the sides of the diaper and the upper portion of the leg opening when they are brought together as the diaper is applied to the baby. Thus, the function of the tab is merely to keep the enlarged portions of the hourglass chassis together.
A side ear, however, is typically used on a rectangular-shaped chassis and applied to the chassis are that forms the back of the diaper. Once the ears are attached, the diaper takes a “T-shaped” appearance, with the “ears” forming the horizontal member of the “T” shape and the rectangular chassis forming the vertical member. As the diaper is applied to the child, the ears are pulled forward and attached to the front of the diaper. The ear not only serves to keep the diaper fastened about the waist, but also will form the side of the diaper and the upper portion of the leg opening.
Furthermore, the elastic used in an ear generally has lower extension and retraction forces compared to the elastic typically employed in tabs. Generally speaking, as the size of the elastic side member increases, the forces necessary to maintain the fit of the diaper are spread across larger area. Also, the larger area means that the force necessary to extend the elastic will increase unless elastic having lower extension forces is used. The higher extension force may make it difficult to extend the side member during the diapering process or during movement of the child while wearing the diaper, compromising both fit and comfort. In addition, if the retraction forces of the elastic are too high, the diaper will fit too tightly, causing discomfort to the child and reddening or abrasion of the skin. Accordingly, it is important to maintain the balance of extension and retraction forces as the size of the elastic side member changes.
As mentioned, both ears and tabs typically employ an adhesive element or a hook-and-loop fastener to enable the diaper to be opened and closed repeatedly. The fastening element, particularly the hook-and-loop type, is a relatively expensive component for a diaper and is a significant contributor to the overall cost of the diaper. Furthermore, as the size of the fastening element increases, the forces necessary to disengage the element to open the diaper increase. If those forces get too high, the outer covering of the diaper may tear or pull apart as the diaper is opened. Thus, it is advantageous to minimize the amount of the fastening element used in the manufacture of the diaper and to use no more than is generally necessary to enable the diaper to remain secured to the child. While this is generally not a problem with side elastic members that are closely matched to the size of the fastening element, it is problematic with elastic side members that are larger in size.
For example, it would generally be considered impractical to apply a hook-and-loop fastener to the entire width of a side component that is 100 mm in width, for example. Thus, the fastener is applied only to a portion of the side elastic component. For example, the width of the hook-and-loop element may only be 30 mm, leaving 70 mm of width of the side member without any fastening element. In such a construction, when tension is applied to the elastic side component, either during the diapering process or during movement of the child, the stress is concentrated in the 30 mm area corresponding to the location having the fastening element. As a result of the uneven stresses, the portions of the elastic side member not having the fastening component tend to curl and become distorted. Apart from an unattractive appearance, the distortion in the ear may result in improper fit of the diaper, and the diaper may fall off, leak, or have other undesirable attributes.
To address these concerns, it is known to use elastic that has a higher elongation forces and/or higher retraction forces. Elastics that require higher extension forces would be less likely to curl or distort when tension is applied to the fastener. By switching to “stronger” elastic, the ear will be more resistant to distortion, but will also increase the cost of the diaper. In addition, elastics that have higher elongation/retraction forces may result a diaper that is too difficult to apply (i.e., takes too much force to extend the ear) or results in reddening of the baby's skin because the retraction forces are too high.
Thus, there is a need in the art for additional ways of making side ears that saves materials, offer less expensive solutions, and still allow for attractive and functional diaper constructions.